In recent years, as an apparatus for recording characters or images on various recording media, an inkjet printing apparatus has been known. Furthermore, in some apparatuses in the medical field, trace amounts of blood are discharged in an ink-jet system.
When a solid material is discharged together with an ink in the inkjet, stability of discharging such a solid material is low since the solid material sediments inside the inkjet. It is disclosed in JP-A-2000-17208 that the solid material is treated to prevent sedimentation of the solid material.